The aim of this study is to determine both safety and effectiveness of three different loading dose regimens of clopidogrel in patients with acute myocardial infarction undergoing primary angioplasty.

This study will enroll STEMI patients, who were planned to undergo PCI, and will randomize them to three different clopidogrel loading dose regimens at first medical contact: no pre-treatment, 600 mg or 900 mg. Platelet activity after administration of clopidogrel will be evaluated by VerifyNow™ P2Y12 point-of-care system.

The study is powered to demonstrate significant differences in the primary end point (the rate of TIMI Myocardial Perfusion Grade=3).

Inclusion Criteria:

• ST-elevation myocardial infarction:

  • chest pain lasting more than 30 minutes
  • not responsive to nitrates
  • ST-segment elevation of more than 0.1 mV in two or more leads on the ECG, or new Left Bundle Branch Block

• With indication to primary PCI, presenting within 12 hour from symptoms onset

• Age > 18 years

• Planned PCI

• Informed Consent

Exclusion Criteria:

• bleeding diathesis
• allergy to study drugs
• pregnancy
• the performance of a rescue PCI after thrombolysis
• known existence of a disease resulting in a life expectancy of <6 months
• lack of informed consent